摘要：We investigate aerosol effects on climate for 1980, 1995 (meant to reflect present day) and
2030 using the NASA Goddard Institute for Space Studies climate model coupled to an
on-line aerosol source and transport model with interactive oxidant and aerosol chemistry.
Aerosols simulated include sulfates, organic matter (OM), black carbon (BC), sea-salt and
dust and, additionally, the amount of tropospheric ozone is calculated, allowing us to
estimate both changes to air quality and climate for different time periods and
emission amounts. We include both the direct aerosol effect and indirect aerosol
effects for liquid-phase clouds. Future changes for the 2030 A1B scenario are
examined, focusing on the Arctic and Asia, since changes are pronounced in these
regions. Our results for the different time periods include both emission changes and
physical climate changes. We find that the aerosol indirect effect (AIE) has a
large impact on photochemical processing, decreasing ozone amount and ozone
forcing, especially for the future (2030–1995). Ozone forcings increase from 0 to
0.12 W m−2 and the total aerosol forcing decreases from
−0.10 to
−0.94 W m−2 (AIE
decreases from −0.13 to −0.68 W m−2) for 1995–1980 versus 2030–1995. Over the Arctic we find that compared
to ozone and the direct aerosol effect, the AIE contributes the most to
net radiative flux changes. The AIE, calculated for 1995–1980, is positive
(1.0 W m−2), but the
magnitude decreases (−0.3 W m−2) considerably for the future scenario. Over Asia, we evaluate the role of biofuel- and
transportation-based emissions (for BC and OM) via a scenario (2030A) that
includes a projected increase (factor of 2) in biofuel- and transport-based emissions
for 2030 A1B over Asia. Projected changes from present day due to the 2030A
emissions versus 2030 A1B are a factor of 4 decrease in summertime precipitation
in Asia. Our results are sensitive to emissions used. Uncertainty in present-day
emissions suggests that future climate projections warrant particular scrutiny.
